function drawVisualization() {
      var options = {};
      // Chart API chart type 'rs' is radar chart
      options.cht = 'rs';

      // set the line colors
      options.colors = ['#00FF00' , '#FF00FF'];

      // fill the area under the lines
      options.fill = true;

      // create a grid for the chart
      options.chg = '25.0,25.0,4.0,4.0';

      var pi = '\u03C0';
      dataTable = google.visualization.arrayToDataTable([
        ['0', 10, 100],
        [pi + '/4', 20, 80],
        [pi + '/2', 30, 60],
        ['3' + pi + '/4', 40, 30],
        [pi, 50, 25],
        ['5' + pi + '/4', 60, 20],
        ['3' + pi + '/2', 70, 10],
        ['7' + pi + '/4', 80, 5]
      // Treat first row as data as well.
      ], true);

      var chart = new google.visualization.ImageChart(document.getElementById('visualization'));
      chart.draw(dataTable, options);
}
